Water-reducible coating composition and process of use thereof

ABSTRACT

Compositions and a method are provided for forming a coated wood, plastic or metal product having the appearance and texture of wood grain. The joints on a wood surface are concealed by the coating and the coating is capable of accepting conventional wood stain.

This is a continuation of application Ser. No. 07/285,519 filed Dec. 15,1988, now U.S. Pat. No. 4,980,402.

The present invention is directed to a method and compositions usedtherewith for coating wood, metal or plastic to render it capable ofreceiving woodgrain printing inks and conventional wood stains, whilealso concealing joints and other imperfections.

In the decorative uses of wood, there are many applications in whichvisible joints in the wood are not desired. For example, in the use ofmoldings along the edges of doors, window frames, and the like, it isdesirable to have each edge constructed of a single length of wood.Moreover, to have a decorative effect, the wood is often stained to adesired color, such as walnut, rosewood, and the like, then covered witha protective coating such as varnish or other conventional clearcoating. The use of single lengths of wood is expensive and wasteful,since short lengths of scrap wood are not reusable. There is nopractical alternative to using single lengths of wood for molding.Plastics or compounded wood pulp products are usually not desirablesince they either do not have sufficient strength and durability or donot have the pleasing wood grain surface texture. A piece of plywoodwould also be extremely expensive since one or more surfaces of themolding would have to be veneered, making it much more expensive then asolid piece of wood.

The use of scrap pieces of wood joined together, such as by fingerjoints, would be desirable. There has been difficulty however, intreating joined pieces of wood to have the appearance of a single pieceof wood for decorative purposes. One such method is described incommonly assigned U.S. Pat. No. 4,546,133, wherein specialized woodcoating and ink compositions are disclosed. The present inventionprovides an improved method and coating for metal or plastic to impartwood-like appearance, or for concealing joints in wood, while stillmaintaining the appearance and texture of a single piece of wood. Thecoating according to the present invention also is capable of acceptingconventional wood stains.

It is therefore an object of the present invention to providewater-reducible compositions which are useful for coating metal orplastic to impart a wood-like appearance, or for coating wood to concealjoints, but which retain the grainy appearance of the natural wood.

It is a further object of the present invention to provide novelcoatings for metal, plastic or wood which accept conventional woodstains.

These and other objects will be apparent from the following descriptionand preferred embodiments.

The present method utilizes a basecoat composition for covering plastic,metal, wood or a wood product comprising a combination of resins,pigments, solvents, and additives for suspension, dispersion,thickening, flowing and defoaming. A printing composition is alsoprovided comprising resins, pigments, solvents, and anti-foaming andwetting agents.

The method according to the present invention comprises the steps ofapplying a novel liquid basecoat onto metal, plastic, natural wood or awood product, evaporating volatile solvents to form a solid coating, andapplying a novel ink composition in a wood grain pattern onto the solidcoating.

The starting material for forming a coated product according to thepresent invention may be any product having a plastic, metal or woodsurface, including strips, with or without joints, sheets, includingplywood and wood grain paper, or any other product derived from wood orwood pulp, sawdust, and the like. Since a primary purpose for the use ofthe compositions according to the present invention is to provide adecorative surface, it is desirable, but not necessary, that thestarting material have a wood grain texture, since that texture will besubstantially retained after the basecoat coating is applied accordingto the present invention.

Generally, the metal, plastic, wood or wood product will be coated witha liquid basecoat composition according to the present invention thendried to remove the volatile solvents. The drying is preferablyperformed with heat in a conventional oven, but other evaporativemethods may be utilized. Then a grain ink formulation may be applied ina pattern to simulate a wood grain using a conventional roller having awood grain pattern using the inks described herein. Apparatus forperforming these functions are conventional and known in the art.

The basecoat formulation according to the present invention comprisesthe following components: acrylic resins, styrene-maleic anhydrideresins, pigments and fillers, thickener, flow agents, defoaming agentsand solvents.

In general, the water-reducible basecoat, according to the inventionwill contain the following:

    ______________________________________                                                           % by volume                                                ______________________________________                                        Water                20-30                                                    Organic solvents     1-5                                                      Styrene-maleic anhydride resins                                                                    0.5-3                                                    Acrylic resins       45-55                                                    Pigments and inorganic fillers                                                                     10-20                                                    Organic thickener    up to 1                                                  Defoaming agents     up to 3                                                  Flow agents          up to 5                                                  Suspension agent     up to 1                                                  Nut shell flour      1-5                                                      ______________________________________                                    

A particularly preferred basecoat composition useful for coating woodcontains the following (percentages given by volume).

    ______________________________________                                                           % by volume                                                ______________________________________                                        Water                23.50                                                    Organic solvents     1.72                                                     Styrene-maleic anhydride resins                                                                    0.8                                                      Acrylic resins       51.10                                                    Pigments and inorganic fillers                                                                     15.98                                                    Organic thickener    0.17                                                     Defoaming agents     1.02                                                     Flow agents          3.33                                                     Suspension agent     0.18                                                     Nut shell flour      2.20                                                     ______________________________________                                    

In a preferred formulation, the acrylic resins and styrene-maleicanhydride resins are the commercially available resins Joncryl 89(Johnson & Johnson), Rhoplex AC-507 (Rohm & Haas), and SMA-1440(Sartomer Company).

Absorption pigments and inert fillers which may be utilized includecommercial pigments such as Asbestine 325 (U.S. Mica), titanium dioxide,talc, Hitox (Benilite), and the like. The composition will also containan organic pigment, pecan shell flour, preferably ground to an averagesize of about 40 micron.

The base coat composition will also contain suspension agents,thickeners, flow agents and defoaming agents. Suspension agents includeColloid 711 made by Colloid Co. A preferred thickener is Cellosize, madeby Union Carbide. Flow agents such as Minusil (P.G.S., Inc.), Super Adit(Nuodex) may be utilized. Defoaming agents such as Surfynol (AirProducts) may be used.

Typical organic solvents include dimethyl ethanol, carbitol (diethyleneglycol monomethyl ether) methyl ethyl ketone, acetone, MIBK (methylisobutyl ketone), methyl and ethyl alcohol, ethyl acetate, amyl acetate,and the like. The several portions of any vehicle used in comparing oneof the decorative coatings are generally composed of the same basicmaterials although they may have varied amounts of thinners, solvents,fillers and the like so as to vary their viscosities and other physicalproperties, but there may be a combination of unrelated resins used onthe same panel to provide texture and growth lines.

The pulverized pecan nut shell flour utilized in the base coatcomposition as an absorption pigment will be in the form of a finepowder, typically grain size of about 35 to 45 microns (preferably 40average microns).

The particular proportions of the various components used may begenerally in the proportions given above.

It will be understood however, that various modifications in proportionsand components may be utilized without departing from the scope of thepresent invention.

A particularly preferred coating composition comprises the following:

    ______________________________________                                                           parts (volume)                                             ______________________________________                                        Water                24.88                                                    Dimethyl ethanol     0.19                                                     Carbitol             1.63                                                     Styrene-maleic anhydride                                                                           0.84                                                     resin SMA-144(H)                                                              Rhoplex AC-507 acrylic resin                                                                       41.33                                                    Joncryl 86-acrylic resin                                                                           12.75                                                    TiPure R900, titanium dioxide                                                                      0.79                                                     Hitox pigment        2.17                                                     Asbestine 325 pigment                                                                              10.46                                                    Nytal 300 talc filler                                                                              3.50                                                     Pecan shell flour (40 micron)                                                                      2.33                                                     Cellosize QP-09-H thickener                                                                        0.18                                                     Defoamer 6-475 (Drew Chemical)                                                                     0.23                                                     Surfynol T.G. (Air Products)                                                                       0.85                                                     Minusil 10 flour additive                                                                          3.40                                                     Super Adit flow additive                                                                           0.13                                                     Colloid 711 suspension agent                                                                       0.19                                                     ______________________________________                                    

In addition to the various pigments mentioned above, the base coat maycontain various typical inorganic pigments useful for wood grain such asthose iron pigments ranging in color from yellow through red, reddishbrown, brown to black, similar to those found in natural wood. Theseiron pigments include yellow ocher, raw and burnt sienna, and raw andburnt umber. Other useful inorganic color pigments include chromeyellow, cadmium sulfide, zinc yellow, cobalt blue, ultramarine blue,iron oxide, chrome green, chromium oxide green, chromium hydroxidegreen, lamp black carbon, and white pigments such as titanium dioxide,titanium calcium, zinc oxide, zinc sulfide, antimony oxide, lithopone,etc. Organic pigments may also be utilized such as toluidine red,phthalocyanine blue and green, VanDyke brown, alizarin, madder lake,lythol red, etc.

After applying the base coat, it is dried, for example, in aconventional oven to remove the volatile solvents, thereby forming ahardened base coat. An ink formulation may then be applied to the basecoat with a roller having a wood grain pattern. The ink formulationcomprises: resins, pigments and fillers, thickeners, defoaming agents,flow agents, suspension agents, solvents, and wax.

The resins utilized in the above ink formulation include acrylic resinssuch as Joncryl 74, BALAB, UCAR-SCT 100. The pigments include variouspigments utilized to simulate wood grain colors, as described above andinclude specifically yellow 895-000-1801 (Nuodex), burnt umber (I-347),red oxide 895-1003 (Harshaw), Mearlin silk white (an iridescentpigment). As an absorption pigment Phoschek P/30 may be utilized. As atinting agent a tint paste such as Benzidine yellow (W-1041) may beutilized. A wetting agent such as glycol ether (PM) is used. Varioussolvents may be utilized such as DMAE (Union Carbide), water andethylene glycol.

The pigments which are utilized in the ink formulation will depend uponthe color of the wood grain desired. The pigments must, of course,impart a color to the ink formulation which is different from the colorof the dried base coat in order to provide contrast. Usually, colorantswhich impart yellow or brown tones to the base coat will be useful.Typically, the base coat, after application of the ink formulation, willbe stained with a conventional wood stain, which usually enhances thecontrast between the base coat and the ink.

In general, the ink will contain as follows:

    ______________________________________                                                        % by volume                                                   ______________________________________                                        Water             2-8                                                         Organic solvents  1-5                                                         Acrylic resins    30-60                                                       Yellow pigment     8-12                                                       Brown pigment     10-20                                                       Red pigment       up to 3                                                     Iridescent white pigment                                                                        up to 1                                                     Inert pigment     up to 5                                                     Wetting agent     2-8                                                         Wax                5-15                                                       ______________________________________                                    

A typical ink formulation may comprise the following (parts by volume):

    ______________________________________                                                               Manufacturer                                           ______________________________________                                        Joncryl 74  52.24  Acrylic resin Johnson &                                                                     Johnson                                      BALAB 3056A .73    Resin (latex) Witco                                        Ethylene glycol                                                                           2.32   Solvent       Chem Central                                 DMAE        .58    Solvent       Union Carbide                                Tap Water   5.15   Solvent                                                    UCAR SCT100 1.20   Resin (latex) Union Carbide                                Glycol Ether PM                                                                           6.41   Wetting agent Ashland                                      895-000-1801 Yellow                                                                       6.22   Pigment       Nuodex                                       W-1041 Benzidine                                                                          4.90   Tint paste    Harshaw                                      Yellow                                                                        I-347 Bt. Umber                                                                           16.77  Pigment       Harshaw                                      895-1003 Red Oxide                                                                        .79    Pigment       Nuodex                                       Mearline Silk White                                                                       .22    Iridescent pigment                                                                          Mearl                                        Phos Chek P/30 fine                                                                       2.45   Absorption pigment                                                                          Monsanto                                     Slip Ayd-459-1029                                                                         10.00  Wax                                                        ______________________________________                                    

After application of the graining ink formulation and air drying, thefinal product may be utilized as is, or stained with a conventional woodstain, then coated with a conventional varnish or other clearpreservative.

The base coat and ink formulation may be applied to any metal, plasticor wood surface, including paper, if desired.

Having described the specific embodiments of the invention, othermodifications and variations will be apparent to those of ordinary skillin the art, which variations and modifications are intended to be withinthe scope of the present invention.

What is claimed is:
 1. A coated product comprising a wood, plastic ormetal substrate and a coating over said substrate formed by placing aliquid coating over said substrate, said liquid comprising:

    ______________________________________                                                           % by volume                                                ______________________________________                                        Water                20-30                                                    Organic solvents     1-5                                                      Styrene-maleic anhydride resins                                                                    0.5-3                                                    Acrylic resins       45-55                                                    Pigments and inorganic fillers                                                                     10-20                                                    Organic thickener    up to 1                                                  Defoaming agents     up to 3                                                  Flow agents          up to 5                                                  Suspension agent     up to 1                                                  Nut shell flour      1-5                                                      ______________________________________                                    

and drying said liquid coating to remove volatile solvents.
 2. A coatedproduct according to claim 1 further comprising a printed pattern uponsaid coating, said pattern formed by imprinting a liquid ink compositionupon said coating, said liquid ink composition comprising:

    ______________________________________                                                        % by volume                                                   ______________________________________                                        Water             2-8                                                         Organic solvents  1-5                                                         Acrylic resins    30-60                                                       Yellow pigment     8-12                                                       Brown pigment     10-20                                                       Red pigment       up to 3                                                     Iridescent white pigment                                                                        up to 1                                                     Inert pigment     up to 5                                                     Wetting agent     2-8                                                         Wax                5-15                                                       ______________________________________                                    

and drying said ink composition to remove volatile solvents.